How to Prevent Underground Storage Tank Flotation

It may seem counterintuitive that an underground storage tank could float. After all, these structures are not only buried under the ground, but they are also incredibly heavy. So why would you need to worry about flotation? The culprit in this situation is buoyancy. Learn everything you need to know about underground storage tank flotation and how to prevent it in today’s blog, below.

How to Prevent Underground Storage Tank Flotation

If you’ve ever wondered how to prevent underground storage tank flotation, Tanks Direct has you covered.


How do underground storage tanks float?

To understand the buoyancy of USTs, think about a water bottle that has been half-filled with water. If you throw the bottle into a body of water, it will float due to the fact that the air within the bottle exerts a strong upward force. This phenomenon is known as buoyancy and the same principle applies to underground storage tanks as well. If flood waters reach a certain stage or the water table rises enough, then the air inside of your UST will begin exerting upward force. Since USTs often contain a large volume of liquid, the force of the buoyancy can be incredibly strong and can even potentially cause your UST to break through the earth above! Luckily, there are a few things you can do to help prevent this from happening.

Preventing underground storage tank floatation


  • Bury your UST deeper. By burying your UST more deeply underground, the weight of the backfill will generate more downward force that will counteract the effects of buoyancy.
  • Use deadman anchors. In cases where burial depth can’t be increased, deadman anchors provide an alternative. Made of reinforced concrete, these anchors will help prevent floatation and also provide additional stability.
  • Use thick paving slab. When placing paving slabs on top of the earth above your UST, using thicker grade paving slab will create more downward force and help keep your UST in place.
  • Install a bottom holddown slab. This concrete paving slab is installed underneath your underground storage tank. The tank is then anchored to the bottom holddown slab which provides downward force that counteracts buoyancy and also offers more stability for the UST.



At Tanks Direct, we have been a nationwide supplier of storage tanks and vessels for 21 years.

  • Nationwide installer of storage tanks and vessels since 1997.
  • Distributor for over 55 storage tank and related accessory manufacturers.
  • Industry leader since 1993.

Contact us today at 800-865-5555, or [email protected] Also be sure to keep up with us on Facebook, Twitter, Google+, and LinkedIn.

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